/Engine/Source/Runtime/Engine/Public/AudioStreamingCache.h
Returns the chunk asked for, or an emptyTArrayViewif that chunk is not loaded. InOutCacheLookupID can optionally be set as a cache offset to use directly rather than searching the cache for a matching chunk. InOutCacheLookupID will be set to the offset the chunk is in the cache, which can be used for faster lookup in the future.
[TArrayView](API\Runtime\Core\Containers\TArrayView)< uint8 > GetChunk ( const [FChunkKey](API\Runtime\Engine\FAudioChunkCache\FChunkKey) & InKey, const [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [FSoundWaveData](API\Runtime\Engine\Sound\FSoundWaveData) > & InSoundWavePtr, bool bBlockForLoadCompletion, bool bNeededForPlayback, uint64 & InOutCacheLookupID )